Traces of Lin’s blood were also found in the refrigerator, freezer, bathroom sink and bathtub, in addition to stains in the rest of the apartment.

Prevost told the jury she also examined 94 police exhibits and found Lin’s blood on many items. Among them were discarded tools: an oscillating saw, two knives, a hammer and a screwdriver.

A large amount of Lin’s blood was also found on a mattress cover, as well as a purple hooded sweatshirt that also had Magnotta’s DNA.

Lin’s DNA was found on a wine bottle the jury has heard was used to sodomize the corpse, but a test for sperm on the victim’s body proved inconclusive.

Prevost only confirmed Magnotta’s genetic profile after receiving a blood sample from the accused earlier this year. Many of the discarded clothing items contained Magnotta’s DNA and sperm, she testified.

Prevost told the jury she watched a so-called murder video to serve as a guide to where to look in the apartment.

The longtime crime-scene forensic biologist with 18 years experience said she watched the video twice — once before entering Magnotta’s apartment in May 2012 and again before looking at the evidence.

“They (investigators) told me what it was briefly and they asked if I wanted to see it, and I said ‘yes’,” she testified.

The jury has not yet seen the video but has been told repeatedly of its existence.

Prevost described what she could remember of the video: a body lying prone on a bed and someone wearing a hoodie who appears to be stabbing the victim with a sharp object.

Later, there is an attempt to masturbate using a severed right arm as well as anal penetration on a mutilated corpse.

Prevost said a small black dog can be seen chewing on a severed limb, while, in other sequences, there were various images of a severed arm in the freezer.

Some of the trace amounts of blood had been diluted, probably in an effort to clean up the apartment, she said.

Diluted blood doesn’t always offer a full genetic profile, but the samples tested provided enough information to identify it as Lin’s, she noted.

Prevost, who is also an expert in blood-stain pattern analysis, said the bed was likely where Lin was struck, given the shape of the blood stains on some surfaces nearby.

The stain on the mattress was particularly large and decayed and had soaked through to the box spring.

Prevost suggested the mattress had been turned to camouflage the stain.

She was also the one who used DNA to positively identify the various body parts as Lin’s.

Earlier on Tuesday, the jury heard from the first patrol officer to enter the apartment.

“Once I entered ... I was struck by a strong chemical smell; it was mixed with the smell of a cadaver,” Peter D’Avola said, adding the stench was something he’d never experienced before.

D’Avola said his primary task was to look for other victims or a suspect, but he didn’t find anyone. During a quick look around, he noted visible red substances he believed to be blood and an oversized bed sheet haphazardly placed on the mattress.

The charges against Magnotta are first-degree murder; criminally harassing Prime Minister Stephen Harper and other members of Parliament; mailing obscene and indecent material; committing an indignity to a body; and publishing obscene materials.

If he gets off I wouldn't be overly shocked, we have had some crazy fucks get off with nothing because of insanity pleas. Good example is that guy who beheaded someone and ate his meat on a greyhound here (canada).